The Andasol 1 thermosolar power plant in Southern Spain, which went on-line in late 2008, has an annual capacity of approximately 179 million kilowatt hours, enough to satisfy the needs of 200,000 people in 50,000 homes, or a city the size of Spokane, WA.

The first parabolic thermosolar power plant in Europe and the largest of its type in the world, Andasol 1 is located on the Guadix plateau, surrounded by the Sierra Nevada foothills in Spain's Granada Province. The 482-acre complex incorporates some 7,500 parabolic trough collectors to capture the sun's heat and convert it to electric power.

In many ways, Andasol 1 is much the same as a traditional thermoelectric power plant. However, instead of fossil fuels, it uses its hundreds of 20-by-40-foot parabolic reflectors to concentrate the sun's rays at 80 times normal intensity onto an array of steel and glass tubes filled with synthetic oil, heating the oil to 735 F. The hot oil is then pumped to an exchange unit where the captured energy is used to drive a steam turbine.

The collectors and their supporting framework were assembled on site using prefabricated galvanized steel parts, mirrors and pipes, and then mounted on pillars connected to the oil flow circuit. Each collector had to be mounted precisely to ensure a high-level of thermal efficiency. The framework also has to be robust enough to withstand decades of vibrations from high winds and temperature variations.

To ensure the framing didn't work loose over time, the project manager ACS-Cobra Group (Madrid, Spain) incorporated approximately 3.4 million Avdelok structural lockbolts from mechanical fastening specialist Avdel (Stanfield, NC) to hold the tens of thousands of pieces in place.

Tests verified that the vibration-resistant lockbolts with their permanently swaged locks between the collar and the bolt would prevent loosening throughout the life span of each collector. The fasteners' large-diameter heads and flanged collars assured uniform clamp load over a broad contact surface.

Operators installed the bolts using 10 HAT electrohydraulic power units and four Avdel 7267 hydro-pneumatic tools. The Avdelok fasteners install in seconds, and the Avdel tools preclude the possibility of operator error, assuring consistent joint integrity with each application.

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